VCS : Configuring Private Network for veritas cluster
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VCS requires you to set up a private network between the systems that form a cluster. You can use either NICs or aggregated interfaces to set up private network.
You can use network switches instead of hubs. However, Sun systems assign the same MAC address to all interfaces by default. Thus, connecting two or more interfaces to a network switch can cause problems.
For example, consider the following case where:
- The IP address is configured on one interface and LLT on another
- Both interfaces are connected to a switch (assume separate VLANs)
The duplicate MAC address on the two switch ports can cause the switch to incorrectly redirect IP traffic to the LLT interface and vice versa. To avoid this issue, configure the system to assign unique MAC addresses by setting the eeprom(1M) parameter local-mac-address to true.
The following products make extensive use of the private cluster interconnects for distributed locking:
- Veritas Storage Foundation Cluster File System (CFS)
- Veritas Storage Foundation for Oracle RAC (SF Oracle RAC)
Symantec recommends network switches for the CFS and the SF Oracle RAC clusters due to their performance characteristics.
Below Figure shows two private networks for use with VCS.
Figure: Private network setups: two-node and four-node clusters
Symantec recommends configuring two independent networks between the cluster nodes with a network switch for each network. You can also interconnect multiple layer 2 switches for advanced failure protection. Such connections for LLT are called cross-links.
Below figure shows a private network configuration with crossed links between the network switches.
Figure: Private network setup with crossed links
To set up the private network
1. Install the required network interface cards (NICs).
Create aggregated interfaces if you want to use these to set up private network.
2. Connect the VCS private Ethernet controllers on each system.
3. Use crossover Ethernet cables, switches, or independent hubs for each VCS communication network. Note that the crossover Ethernet cables are supported only on two systems.
Ensure that you meet the following requirements:
• The power to the switches or hubs must come from separate sources.
• On each system, you must use two independent network cards to provide redundancy.
• If a network interface is part of an aggregated interface, you must not configure the network interface under LLT. However, you can configure the aggregated interface under LLT.
• When you configure Ethernet switches for LLT private interconnect, disable the spanning tree algorithm on the ports used for the interconnect.
During the process of setting up heartbeat connections, consider a case where a failure removes all communications between the systems. Note that a chance for data corruption exists under the following conditions:
• The systems still run, and
• The systems can access the shared storage.
4. Configure the Ethernet devices that are used for the private network such that the autonegotiation protocol is not used. You can achieve a more stable configuration with crossover cables if the autonegotiation protocol is not used. To achieve this stable configuration, do one of the following:
• Edit the /etc/system file to disable autonegotiation on all Ethernet devices system-wide.
• Create a qfe.conf or bge.conf file in the /kernel/drv directory to disable autonegotiation for the individual devices that are used for private network.
5. Test the network connections. Temporarily assign network addresses and use telnet or ping to verify communications.
LLT uses its own protocol, and does not use TCP/IP. So, you must ensure that the private network connections are used only for LLT communication and not for TCP/IP traffic. To verify this requirement, unplumb and unconfigure any temporary IP addresses that are configured on the network interfaces.
The installvcs program configures the private network in the cluster during configuration.